Arc lamp



C. A. GREEN Aug. y

ARC pun Originai Fil 11, 1922 2 Shuts-Shut 1 Original Filed Oct. 1 9

C. A. GREEN ARC LAMP 2 Shoots-Shoot 2 Cfiarls Q1 (746,671

terial, preferably aluminum.

Patented Aug. 10, 1926.

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PATENT osrifcsf.

COM IY I 'A ABC LAMP.

Application aledpetober'll, 1832, Serial No. 593,872. I Renewal June 14, 1828.

This invention relates to improvements in uc lamps arranged in groups for uniform-lighting in connection: with blue print machines, photo-engraving,l and other arts.

Heretofore' continuous ue printing has been carried out by .ieeding the tracings and blue print paper: onto an endless belt which passes a series of are lamps arranged in a'row. Due tothe blowing aside of the arcs, caused by the magnetic fields established by the lamps, the intensity of the light varies, resulting in a lack of uniformity and in some cases causin streaks.

'ihe object'of the present invention is to overcome this difliculty b providing certain improvements intheetailed construction of the individual are lamps and their relation to ea'eh'other, resulting in uniform distribution of the lightwover .an extended area.

Certain other improvements are claimed in my divisionalapplieation 38,069, filed June 18, 1925.

The improvement is explained in connecalthough the invention is not limited this embodiment thereof.

In the drawings- Figure 1 is an elevation, partly in section," of a part of a blue print machine;

Fig. 2 is a top plan view of the row of arc lamps used therein; and I Fig. 3-is an elevation of said are lamps. The blue print machine comprises a suitable frame 1 havi a table 2 over which the operator slides t eblue print paper on which the tracings are superimposed. The tracings and the blue rint paper travel rearwardly under a gui e 8 and upwardly along an endless belt- 4, whiehslides over curved lass support 5, and is supported and mov by a series of rollers 6, 7, and 8, the'roller 6 constituting the driving roller. The-printing is done as the prints travel slowly past the curved sheet of glass, the

' tracings andbluemprints issuing at the top of the machine a being fed forwardly on to a sheet metal supporting plate 9, over which they slide into a sheet metal receptaole 10.

The are lamps are supported on a transverse pipe or conduit 11, carried by the frame of the machine, each lamp having a supporting frame 12 of nonetic mahe lower tion with a continuous blue print machine,

end. of this framesurrounds-the conduitll, providing a hinged support'which permits the lamp. to. be swung forwardly for'. in-

spection or trimming. The aluminum frame carries a supporting plate'13 of magnetic material, such as cast-iron, on which the various partsof the arc lamp are mounted. The mechanism for feeding the carbon downwardly is .mounted on this support andincludes a solenoid 14 and'suit' able clutch. mechanismv forming no apart. 0 the present invention. I. g

A glass globe 15 ismounted on an extension 16 constituting part of the arc lamp aluminum frame... A reflector 17:isar-- ranged in front of the globe to distribute the light evenly to the rear over-the. blue pr nt paper. In th arc lamps used heretofore, the 'arc which formed betweenthe upper and lower electrodes or carbons had a tendency. to blow to one side, as an iron frame was employed as a support. for the structure.- It was, therefore, neoassary to mount the: solenoid or magnet in each lamp fairly high above the points of the carbons, resulting in a lon lamp. In the present construction the rame is made of aluminum, which has a number-of very desirableproperties, including its non-magnetic propertyfand. said frame is mounted below the solenoid the latter bein mountedznot'far above the arc and the imp being correspondingly shorter. In this construction, and with the arrangement of the arc lamps in a row, as shown in Fi arc to, one sidi has been greatlyminimized.

Referringto Fig. 3, the are which forms, between the carbons 18 and 19in each case has a tendency to blow to the right, this tendency being offset, however, byth magnetic' field established by the solenoid of the adjacent lamp. The right hand lamp. having no lamp to the right of itto'compensate in the manner described,'.I provide. a stripof magnetic material20, preferably apiece of mild steel, which is secured to. the rightli'and lamp of the group, as shown in Figs. 2 and 3. -Said" strip bri the magnetic field in such proximity to t e are as to counteract its tendency to blow to the right. As a result of this arrangement the are is comparatively steady and centrally located with reference to the carbons.

In the prior constructions, previously re- 2 and 3, the bowing of the ferred to, the arc in blowing out to one side would consume one side of the carbon, the upper end of the are terminating at a point considerably above the lowest point of the carbon, the lower end being unsymmetrical in shape. This projecting lower point caused a shadow to be thrown which interfered with uniform printing.

lVith the present arrangement the upper carbons are symmetrical in shape at their lower extremities and the arc travels slowly around said lower ends consuming them evenly and furnishing a light which is free from shadows.

As shown in Figs. 2 and 3, the supply wires 21 enter the conduit 11 with branch connections issuing from the outlet boxes 22. Figs. 2 and 3 also show a slightly diagonal arrangement of each lamp with reterence to the axis of the supporting conduit. This arrangement results in some im provement in the magnetic field.

In the absence of the improvements described bowing ot' the arcs occurs and disturbs the uniformity of the lighting etlect.

At the upper end of each globe, and within the same, is a casing 23 having suitable holes 24 in it to permit the escape of heated gases. By virtue of the smaller construction of the frame and associated parts, previously referred to, I am enabled to use a smaller globe, which, in turn, results in drawing in the outside air more advantageously, the air being drawn in at the top of the globe and expelled intermittently through the same openings, as the successive installments of air heat up and expel themselves. Under these conditions less oxygen is drawn in at a time, and there is less irregularity in the heating. This permits the use of said smaller globes without danger of cracking them.

The construction described also permits the use of higher voltages with increase of current and correspondingly longer and heavier arcs. The longer arcs emit a greater proportion of rays effective for blue printing and photography generally than the shorter arcs, and increase the printing speed. lVith my improved construction I am enabled to increase the current used twenty-five per cent with an increase in printing speed of about one hundred per cent, with improved results from the standpoint of uniformity in the prints.

The improvements described herein are applicable both to alternating current and direct current lamps, although the improvement over the prior practice is more pronounced in the case of lam s used on alternating current circuits. eretofore it has been necessary to design arc lamps specially for alternating current or direct current use as applied to photographic work, whereas with my improved construction the same lamp may be used in either work, making lamps being so arranged that the magnetic field of one opposed by the next lamp in the region of the arc of the first lamp to minimize bowing of said arc, and means associated with the end lamp of said series to compensate for the absence of an additional lamp beyond the same. In combination, arow of arc lamps having a non-magnetic support for the per c 30!. thereof, a solenoid above said carbons arranged on one side of the axis of said carbons, and a magnetic member arranged adiacent the carbons of the last lamp of the row on the opposite side of the axis thereof from its solenoid.

3. An arc lamp comprising a non-magnetic support for the lower carbon, a solenoit mounted in elevated position, a magnetic supporting structure below said solenoid and above the region of the arc, and a magnetic member dependingtrom said structure to the region of said are.

An arc lamp comprising a magnetic su iiporting plate, a solenoid mounted thereon above the same, a non magnetic frame depending from said plate to support the lower electrode, and a strip of magnetic ma-. terial depending from said supporting plate. V

5. A series oi. arc lamps each having electrodes in alinement, a solenoid mounted on one side of the axis of each lamp, each lamp being mounted with its solenoid slightly out of the line connecting the axes of the respective carbons, a non-magnetic support for each lower carbon, and a reflector asso-. ciated with each lamp, whereby the magnetic field of each influences the nextone to prevent the establishment of a bowed are in a lixed plane, thereby providing a uniformly distributed source of light.

In testimony whereof, I have subscribed my name.

CHARLES A. GREEN. 

